Semiautomatic firearm converted to full automatic



March 29, 1949. F w SAMPSON ErAL 2,465,487

SEMIAUTOMATIC FIREARM CONVERTED To FULL AUTOMATIC Filed Oct. 28, 1.944 3 Sheets-Sheet 2 FREDERICK VV-.EAMPSDN March 29, 1949. F. w. sAMPsoN ErAL 2,465,487 SEMIAUTOMATIC FIREARM CONVERTED TO FULL AUTOMATIC 5 Sheets-Sheet 5 Filed Oct. 28, 1944 .05. .mik

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FREDEWEKWEAMFISQN, PAUL H HAM|5L:H?

Patented Mar. 29, 1949 SEMIAUTOMATIC FIREARM CONVERTED TO FULL AUTOMATIC Frederick W. Sampson and` Paul H. Hamisch,

Dayton, Ohio, assignors to General Motors Corporation, a corporation of Delaware Application October 28, 1944, Serial No. 560,828

(Cl. Sil-140) 12 Claims.

This invention relates to firearms, particularly to the type of iirearm known as a carbine and disclosed, for example, in Patent No. 2,308,283 to Humeston. The invention is specifically concerned with the provision in such a weapon of means whereby it not only may be operated as a semi-automatic weapon but also selectively may be operated as a full-automatic weapon.

The basic carblnes, of which the present invention represents an improvement, are characterized as gas-operated, self-loading, aircooled shoulder weapons delivering semi-automatic re controlled by the operator. The basic carbine is said to be semi-automatic in that when the trigger is operated rearwardly, assuming a round to be in the chamber, the hammer to be cocked and a reserve of ammunition to be in the magazine, a single shot is fired and thereafter the gun will automatically extract and eject the empty case, cock the hammer and chamber another round. The cycle may then be repeated by allowing the trigger to return to forward position and again moving it to rearward position.

` The carbine of this invention may be red semi-automatically as described in the immediately preceding paragraph, but upon throwing a selector arm may be operated fully automatically, that is to say, continuous fire may be delivered merely by holding the trigger in rearlward position. Continuous iire may be interrupted by releasing the trigger and such lire will also cease upon exhaustion of the magazine.

It is, therefore, an object of this invention to provide a rearm selectively operable as a semiautomatic or full-automatic weapon. A further object is to provide a carbine of the type described in which, by the addition of a minimum number of simple parts, full-automatic re may selectively be achieved. A further object is to provide alternate and additional parts for such a carbine which may readily be incorporated in the model now in service to modify it for selective full-automatic or semi-automatic fire.

With these and other objects in view, as will more fully appear, reference is had to the following description of one embodiment of the invention taken in connection with the accompanying drawings in which:

Figure 1 is a partial sectional right side view of a carbine embodying the invention as set for full-automatic operation and showing certain parts in iiring position,

Figure 3 is a view similar to Figure 1 showing certain other parts in firing position,

Figure 3 is a view similar to Figure 2 showing 2 the parts immediately after the hammer has struck its blow,

Figure 4 is a view similar to Figure 3 showing the parts in another stage of cyclic operation,

Figure 5is a left side view of a portion of the carbine,

Figure 6 is a section taken along the plane 5-6 of Figure 5,

Figure 7 is a View similar to Figure 1 showing the Carbine set for semi-automatic operation, and

Figure 8 is an exploded view of the principal parts embodying the invention.

In the several views like reference characters refer to identical parts.

Turning now in particular to Figures l through 4 of the drawings, the carbine shown has a stock l, containing the barrel and receiver group, the operating mechanism group, and the trigger housing group. A hand guard 2 overlies the rear part of the barrel with hand guard liner 3 in contact with the rear end of the barrel, the hand guard being secured to the stock by a front band (not shown) to unite the several groups into a whole.

The barrel and receiver group includes the barrel 4 which is provided with chamber 5 accommodating a round of ammunition having a cartridge case 6 and bullet 1. Aii'ixed to the under side of the barrel is a gas cylinder 8 and at the rear of the barrel is aiXed integrally therewith the receiver 9 having a raised portion I 0 upon which is mounted the rear sight (not shown). At the extreme rear of the receiver is a lug I I lockingly engaged in a recess formed in recoil plate I2 fastened to the stock by means of screw I3. The gas cylinder communicates with the bore of the rifle in conventional manner and is provided with gas piston I4 capable of limited reciprocal movement in the cylinder.

The operating mechanism group includes the bolt I5 having the usual firing pin reciprocable therein, the operating slide assembly I6, the operating slide spring I1 and the operating slide spring guide I8. The retracting handle I9, integral with the slide, is used for .manually re- -tracting the slide and bolt against resistance of spring II. Under gas operation, piston I4 moves rearwardly, strikes the body of the operating slide and propels the latter in recoil in known manner against the force of the operating slide spring.

The trigger housing group includes the trigger housing 20 having an integral trigger guard 2l. As best shown in Figure 1, lthe rear of the triggerhousingis attached to the rear of the receiver by a T-shaped lug 22 on the housing which engages a corresponding recess formed in the lug 23 of the receiver. The forward end of the trigger housing it attached to the receiver by a pin 24 passing through upstanding ears 25 on the forward end of the housing and through de pending lug 26 on the receiver (see Figure 6). A vertical opening 21 is provided by the forwardr part of the trigger housing for the reception of a magazine (not shown). A magazine catch 28 is positioned at the rear of the opening to engage the magazine to hold the same in the carbine.

Also included in the trigger housing group is the trigger 29 pivoted on trigger pin 30 fixed in the housing 20. A trigger spring 3| yieldingly urges and normally maintains the trigger in forward position as shown in Figures 1 and 2. A sear 32 is pivoted on the trigger pin 30 between arms 33 of the trigger. A hammer 34 is pivotally mounted on hammer piny 35 carried in the side walls of the trigger housing. A sear notch 36 is formed in the hammer to engage with the nose 31 of the sear for holding the hammer cocked as shown, for example, in Figure 2. The hammer spring plunger 38 seats in a notch 39 in the rear face of the hammer shank and the rear end of the plunger is loosely received in an aperture 40 in the rear of the trigger housing.

Hammer spring 4|` surrounds the shank of the I plunger, seats in a counterbore 42 in the rear wall of the trigger housing and bears against a shoulder on the forward end of the plunger to urge the plunger forwardly and to rotate the hammer forwardly when released.

Received in suitable bores in the trigger and sear is sear spring 43 tending to tip the nose of the sear upwardly. The sear is provided with elongated slot 44 permitting limited longitudinal movement as well as tipping movement of the sear upon the trigger pin. The sear spring also urges the sear forwardly as shown in Figure 4.

The foregoing description of the parts of the carbine according to the invention would apply equally as well to the weapon illustrated by the aforementioned patent to Humeston and affords adequate basis for the immediately following explanation of the operation in semi-automatic fire of any of the carbines referred to.

' Referring now to Figure 'I of the drawings there is shown the carbine of the present invention set for semi-automatic operation with the bolt closed and locked, the hammer cocked and the trigger in forward position. Assuming a round of ammunition to be in the chamber and a loaded magazine to be in position, the trigger 29 is moved rearwardly and pivots clockwise about the trigger pin 30. Sear seat 45 engages the underside of rear sear arm 46 tipping the latter upwardly, pivoting the sear on trigger pin 30 and depressing the nose 31 of the sear to disengage the nose from sear notch 36 of the hammer. Under inuence of energy stored in hammer spring 4|, hammer 34 is rotated forwardly to strike the firing pin in bolt I to fire the chambered cartridge. The ring cycle is so rapid that ordinai-ily the trigger is held in full rearward position until after completion of the cycle.

When the bullet has progressed beyond the port leading to the gas cylinder, bore gases under pressure enter the cylinder, move the piston rearwardly which, in turn, propels operating slide I6 to the rear against the action of operating slide spring |1. The rearward movement of the operating slide unlocks bolt I5 and moves the bolt to the rear to extract the empty cartridge cas and eject the same when it has cleared the breech. During rearward movement, the underside of the bolt engages the top of the hammer to rotate the same rearwardly and downwardly. The bolt and hammer are so related that the hammer, in rearward movement, overrides its cocked position allowing the nose of the sear to slide forward on trigger pin under action of sear spring 43 and as permitted by the elongation of slot 44 to tip upwardly into the rearward extension of the sear notch 36. Such motion of the sear results in its taking a position with respect to the trigger substantially as shown in Figure 4, wherein the rear arm 46 of the sear rests in the depression 41 of the trigger and in front of the sear seat 45. Upon return of the hammer from overriding position to cocked position, the hammer, sear and trigger assume the attitudes shown in Figure 4 and the hammer is held in cocked position as the bolt is. propelled forwardly by the operating slide I6 under action of operating slide spring l1. The bolt in Aits forward motion picks up and chambers a fresh cartridge and becomes locked to the barrel to. complete the cycle.

It will be observed that, with the trigger back and the rear arm of the sear resting in depression 41 of the trigger, the sear cannot be tripped by the trigger until the latter has been released and allowed to spring forward as urged by spring 3| thus depressing sear seat 45 beneath sear arm 46 to clear the way for slight rearward movement of the sear to place the rear arm of the sear in position again to be engaged and tipped by the sear seat upon another pull of the trigger. Such rearward movement of the scar takes place under urge of hammer spring 4| as levered through the hammer 34, the sear notch 36 of which is engaged with the nose of the sear, to push the sear rearwardly on trigger pin 30 as permitted by elongated sear slot 44. The sear spring 43 yields to the rearward sear movement.

Keeping in mind the above description of the Carbine and its operation in semi-automatic fire, there will now be described the additional parts provided in accordance with the invention for converting the Carbine to a full-automatic weapon. Such additional parts comprise a sear trip 48, a sear trip lever 49, a selector crank 50, a selector 5|, and a selector spring 52 (see Figure 8). It may here be remarked that certain of the parts common to the Carbine of this invention and that of the aforementioned Humeston patent have been appropriately and slightly modified to accommodate the additional parts required for full-automatic functioning. Notably, the sear, hammer and operating slide have been so modi* fied.

Sear trip 48 is pivotally carried by hammer pin 35 for limited rocking movement. The sear trip has a body portion 53, inturned sear tripping ringer 54, plunger housing 55, and sear trip lever engaging arm 56. A sear trip plunger 51 is reciprocably-carried in a cylinder formed in housing 55 and is backed up by a sear trip plunger spring 58 (see Figure 2). A vent 59 is provided in the bottom of housing 55 to prevent entrapment of air in the plunger cylinder and consequent sluggish plunger action.

Sear trip lever 49 has a pivot hole 60, rear arm 6|, front arm 62 and upstanding terminal finger 63. A

Selectorfcrank 50 (Figure 8) has a pin 24,

previously described ,in connection with the forlward mountingI of the trigger lhousing Aandan integral crank arm 65, the latter having a sear` trip lever pivot 66 integral therewith; The distal end of the pin 24 is notched on opposite sides at 61 to provide one element of a joint for engagement `with selector 5|.

Selector 5| is provided with slot 68 mating with the crank pin notches 61. It has a rising selector arm 69 and a rearwardly extending arm 1U havinga recess 1| receiving the end of the selector spring 52. (Figures2to 4.) l y Selector spring 52 is a simple bowshaped spring provided at its rearward end with a loop 12 received in a recess in the trigger housing.

kThe selector mechanism and full-automatic parts, shown exploded in Figure 8, are shown assembled and in various stages of full-automatic operation in Figures 1 through 6. They are also shown in inactive positions in Figure '7.

`As best seen in Figure` 2, the sear trip 48 is piyoted on the hammer pin 35 adjacent the hammer. The sear trip lever is mounted on pivot 66 carried by selector crank arm 65 on selector pin 24 which, in turn, carries the selector 5| mounted on the opposite end` of the pin. Selector spring 52 `is shown in position, the forward end of the spring being received in the end of arm and the rearward end of the spring being received in the trigger housing.

Figures 1 and 2 show the carbine ready to be red. When the trigger is pulled, the rear arm of the sear is tipped up, `as shown in Figure 3, and the nose of the Sear is rotated out of the sear notch of the hammer to releasel the Ahammer for forward rotation. The sear then moves very slightly forward on the trigger pin until it comes torest at 13 against the rear face of sear tripping nger 54 of the seartrip 48. Rear sear arm 46 still overlies the forward part of sear seat 45.

After the hammer has struck the firing pin and the bullet has progressed suciently far in the bore. of the carbine to admit gas to the gas cylinder, as previously explained in connection with semi-automatic operation, the gas piston moves the` operating slide I6 to the rear. The slide is provided with a downwardly facing cam, consisting of an upper forward horizontal surface 14, a rearwardly and downwardly inclined cam surface 15, and a lower short horizontal surface or dwell 16. Before the slide begins to move rear wardly, finger 63 engages the extreme forward part of the lower cam surface 16. During the firstpart of the slides rearward movement, the tip of the nger is levered upwardly, by action of sear trip plunger spring 58 (Figure 2), as will presently be described, to follow inclined surface 15 and to cease upward rotation at a level adjacent upper cam surface 14. The first part of the rearward movement of slide I6 may be described as free movement, since it takes place prior to the `rotational unlocking of the bolt, which latter begins substantially at the moment when the tip of finger 63 arrives at the upper cam surface 14.

As finger 63 rotates upwardly, the forward end of sear trip 4B is forced downwardly to the positionshown in Figure 4 by action of sear trip spring 58 which bears against plunger 51 which in turn bears against a lower portion of the receiver 9. Sear trip lever engaging arm 56 is provided with a downwardly open slot 11 in which is received the end of rear arm 6| ofj the sear trip lever. Depression of rear arm 6| causes pivoting of thesear tripleverabout pivot 66 thus causing 6 the tip of linger 63 to rise as permitted by the rearward recession of` cam surfaces 16 and 15.

During travel of the operating slide and bolt` to full rearward position, the usual extraction and 5 ejection of the empty case occurs together with rearward rotation of the hammer. At the time in the operation when the hammer has just overa ridden cocked position under recoil of the bolt, as previously described, the sear is urged, by seai spring 43, fully forward on the trigger pin 36 and the rear arm 46 of the sear is tipped into the depression 41 of the trigger to assume the position shown in Figure 4. During such movement of the sear, the sear shoulder 13 slides under the `raised sear tripping nger 54 and the sear nose is positioned high, so as to engage the sear notch of the hammer when the latter is freed of the bolt.

magazine a fresh round and chamberng the same. Near the end of forward movement of the slide, the bolt is rotated to locked position, which rotation is completed just prior to engagement of the cam surface 15 with the tip of finger 63 of the sear trip lever.

The last increment of forward movement of the slide after completion of the rotation of the bolt to locked position is so called free movement,

,iduring which inclined surface 15 cams the forward 4end of the sear trip lever downwardly, pivoting the rear end of the lever upwardly. The forward arm of the sear trip 48 thus is pivoted upwardly and the sear tripping finger 54 is rocked downwardly against the top of sear 32 (Figure "4) to rotate the nose 31 of the sear out of the hammer sear notch 36 to begin a new cycle. It

will be observed that the bolt is completely locked before the hammer can be released.

40, Subsequent cycles will be repeated so long as.

shoulder of the sear seat abutting the rear end of the rear sear arm `46. During such cycles, substantially the only movement of the sear is the oscillating motion imparted downwardly by the sear tripping nger 54 and upwardly by the sear spring 43.

As stated, full-automatic fire may be stopped by releasing the trigger. The downwardly projecting portion of the lower side of the trigger snaps forwardly when released, after which the parts come to rest as shown in Figures l and 2, the sear having been levered back on the trigger pin by the hammer spring acting through the hammer and sear notch 36. In this position, when the slide returns to battery the sear trip finger 54 is depressed, as explained, but it does not trip the Sear. Instead, this finger moves idly down in frontof the shoulder 13 of the sear and stops in the position shown in Figures 1 and 2.

In Figure 7, and in dotted lines in Figure 5,

there is shown the relationship of the parts when the selector arm 69 has been thrown rearward to.

. position for semi-automatic fire. The two positions of selector arm 69 are best shown in Figure 5. The forward position (full lines) permits fullautomatic fire and the rearward position permits semi-automatic re. `The vtop of arm 1li limits Aforward movement of the selector arm by abutting. the-under surface or receiver Thelbottom'. of arm 1z0V limits rearward. movementof the sel lector arm by abuttinganupper surface; ofi trigger housing- 20. The. selector. springilyieldingly retains the selector arm in either of the two; posi.-l tions.

As best seen in Figure 6 and comparison of: Figures 3- and 7, thefmotion. of the selector arm. is'imparted to crank arm 6.5 and. sear trip.` lever pivot. 8B through pin 24. When the. lever: pivot 6d is in itslowest position, as seen in Figure 7, the sear tripv plunger housing 5.5 is;fu1ly depressed; and the sear tripping finger 54 is fully raised. Reciprocation ofl theoperating slidenow willinot; actuate the sear trip. The othery parts. of the carbine are thus free to operate serni-autov matically as has been described, whichisssimilar: to theffunction of correspondingpartsofrthe Pat.- ent No. 2,308,283 toHumeston..

It. will be seen that there. has been provided ai firearm capable of either'full-automatic or semi automatic re and in which the mechanism forv tripping the sear in full-automatic're issimple in-construction and safe andpositive ineoperation'. As previously mentioned, the. sear is. nottrippedv until the bolt is closed and locked.. Moreover,u the sear. is not tripped until the slide is substantially fully in battery, in which position the, slide must be ifthe gas piston is'to actuate the. slide properly. The gas piston isvlimitedin rearward movement to a short distanceof about. 9./644 of` an inch. The operating slide must' be in contact with the gas piston during such limited mover ment of the latter in order that the: slide may acquire. suiiicient momentum to, be propelled: tov its rearward position. This condition is assured. by providing appropriate cam surfaces on the. slide itself and means coacting therewith'totrip; the sear in full-automatic operation: only after the slide has substantially returned to.. battery. The cam recess 83 in the operating slide,` by.'

which the locking lug 80. of. the. bolt is rotated; is`r formed with a rearward terminalhorizontal ex'- tension (open on thelower'sideof the slide) in.

which the lug 80 is received after completion; of

rotation of the bolt to full locked: position, and. themovement of the slide in counter recoil extends far enough to bring this lugv into, andnear` the rear end of, the horizontal part of the-recess 83 when the gaspiston of the arm-is fully pressed' to it forward limit by the slide' I 6. Thegas piston serves to limit the forward movement'of theslide.

In order to attain maximum rapidity 0.1'.VV auto matic iire, the length of thesear trip lever arm 6| and nger 63 are soproportionedthatfthesearl trip 48 is rotated a sufficient amountv to operate" thesear 32. tol a let-off positionjust. asthe slide- I6 abuts the gas piston. In.practice,.this let-oil'j occurs when the finger 63 has beeny wiped by' the upper half, or slightlylmoreof the inclined cam face 15. the sear trip 48 is such that itsarm 5dr engagesA the sear 32 to move the sear. nose 3l out from under the trigger notch 36 just beforecompletion" of movement of the slide tobattery position.

It should be notedthat' in moving the selector from automatic-lire position to semi-automatic position, the fulcrum representedV by the-V pin 66 is' not only lowered, tending to positionv the finger 63. below the carri` facesv 'I5- 16, but is also moved forward, tending to `position the nger- 63 forwardly toward the forward@limit'ofrecipr cation of the. cam face T51 Utilization of these twoicomponents'of direction makes it possible to- Thus, the. angular movement of'v maticrre withk a. veryy small degreev of movement of the selector.

The foregoing description is merely illustrativev of the invention and is. not to be considered as limitative. While the. invention has been de scribed with specific reference to carbines of the typezillustrated by Patent 2,308,283 to Humest'ou, it will.'v be understood that: its principles may' applied to other firearms without. departing from. the' spirit and scope of. the invention as" deiinedi in the following claims.

1. An. automatic firearm comprising' an. operate ing slide.; a breechl bolt retracted. byv saidv slide uponf recoil and: returnedto` battery' byv Said slide upon counterrecoil, said breech bolt extracting andi ejecting an empty; cartridge case. upon recoil and. chambering a fresh round` ofv ammunitionv upon counterrecoil, a hammer pin, a. hammer pivoted on: said hammer pin and having. an arcuiater lower' surfaceA providing. a sear notch,v saldi hammer being; cocked by said breech. bolt upons. retraction, atrigger pin,.av sear pivoted'upon said. trigger pin, engageable in said sear notchandi having an' elongated: pivot` slot, a trigger pivotect upon said trigger pin, a sear spring between saldi sear and said trigger yieldingly urging; said sear" to a forward position inl which thef rear endzoffi said sear slot abuts said trigger" pin, said". sean being movable to arearward positionagainst:A the action offv said searspring in whichrlatter positiom the; forward end of said'sear slotz abuts said trig-` ger pin, a sear seat. on: said trigger trippingly` engageablewith said sear when: the sear is'. in: rearward position a shoulder on. said trigger engageablewith. said sear to hold' said sear. inf. forward position, ar sear tripy rockablyf pivoted'v on: said hammer pin trippingly, toengage a.y portion:v of saidfsear when saidfsear'is'in-forward position, said. sear having a recess into'which1said1sear tripdly may-rockwhen said'sear is in rearward; position, a pivoted seary trip lever havingian'amnr forrocking'. said sear trip; and having another' arm, cam means on said slide;slideablyengaging'.

tripas said slide comes into. battery, av movably mounted.A pivot. carry-ing saidisearA triplever', and.:

selector means for moving: saidzl sear'4 trip. lever pivot to position the saidother arm of' said''seaxrv y trip. lever in. inoperative. position with respectftoi a sear. in operativerelation tofthe trigger" and@ hammer, ,the combination therewithof,v a member.' roclc'ably pivotedadjacent` thehammerand havel inga. finger.. at one end extending transversely/of.y thefirearmand directedinwardly thereof andi4 positioned to engagethe hammer-engaging por-'- tion. of. the sear: on. rocking, said .member having; a finger. at. the.- other'. end. also transverse f to,A the firearm but extending outwardly thereof,.a pivot;-4 pin.l a lever mediallypivoted to.. thefirearml on said'pivot. pin and having one of itsfendsfinen gagement with the secondmentionedliinger and.. the other of; its ends. in engagement. with the1 operating slideV whereby the said second. men, tioned end of saidv leverv is depressedwhen. the operatingzslide is .at the battery position, resilient. means onl the said second mentionedfi'ngerb'ias ing' the said' first mentioned linger.v free of. sai'd sea-i-4 when the4 said first' mentioned endf off said", lever isf'reed for'motioxrl uponl disengagement of `alicimisv the said second mentioned end of the said lever l from the slide, a crank arm attached to said pivot pin, stop means, a rockable means actuated between said stop means and secured to said crank arm for bodily adjusting said pivot pin whereby said lever is moved into or out of operative engagement with the slide, and spring means associated with said rockable means for holding the same against either stop means.

3.V In an automatic weapon having a receiver,

a slide reciprocably mounted on said receiver, a

hammer oscillatively mounted in said receiver, a trigger pivotally mounted on said receiver and a sear tiltably mounted on said receiver adjacent the trigger and releasably engageable with said hammer, the combination therewith of a pin `rotatably mounted in the receiver, a crank means mounted on said pin, a manually operable mounted selector arm positioned externally of said receiver and secured to said pin, snap acting spring means rcleasably retaining said arm in either of two limit positions, a iirst lever pivotally mounted oppositely from said sear tripping portion andv operable in the plane of the said first lever, an offset plunger housing on said body portion, and

i 'a spring pressed plunger in said housing adapted Wtoabut said receiver, whereby in one limit position of said selector arm said `iirst lever engages `said abutment member upon actuation of said follower portion by the slide causing said sear tripping portion to trip said sear to release the hammer, and in the otherlimit position of said selector arm said first lever isinoperative to engage said abutment memberto eiect such release `of the hammer.

4. In an automatic weapon having a receiver, a slide reciprocably mounted on said receiver, a hammer oscillatively mounted in said receiver, a trigger pivotally mounted on said receiver and i a sear tiltably mounted on said receiver adjacent the trigger and releasably engageable with said hammer, the combination therewith of a first lever, a fulcrum means therefor in said receiver, a follower' portion on said first lever adapted to be actuated by the slide, a second lever having a body portion pivotally mounted in the receiver, a sear tripping portion extending from said body portion and operable in the plane of the sear, an

abutment member extending from said body portion and operable in the plane of the said rst lever, a spring pressed plunger means in said body portion adapted to abut said receiver and means for adjusting said fulcrum means whereby in one position of the same the said cam follower portion is actuated by the slide causing said sear tripping portion to trip said sear to release the hammer, and in another position said rst lever is inoperative to engage said abutment member to effect such release of the hammer.

In an automatic weapon having a receiver, a slide reciprocably mounted on said receiver, al oseiliatively mounted in said receiver, a

trigger pivotaliy mounted on said receiver and a tiltabiy mounted on said receiver adjacent the trigger and releasably engageable with said hammer, the combination therewith of a rst lever mounted on the receiver, a follower portion on one end of said first lever adapted to be actuated by the slide, a second lever pivotally mounted in the receiver and having portions operable in the respective planes of the sear and said first lever for respective engagement therewith and means for bodily adjusting said first lever in the plane of motion of said first lever whereby in one position said follower portion is actuated by the slide for causing said sear to release the hammer and in another position of said first lever the same is inoperative to eiect such release of the hammer.

6. In an automatic weapon having a receiver, a slide reciprocably mounted on said receiver, a hammer cscillatively mounted in said receiver, a trigger pivotally mounted on said receiver and a sear tiltabiy mounted on said receiver adjacent the trigger and-releasably engageable with said hammer, the combination therewith of a first means movably mounted on said receiver for motion in a first plane, a follower portion on said iirst means adapted to be engaged and actuated by the slide, a second means mounted in the receiver for movement in a second `plane parallel `to said first plane and having a sear tripping portion and an abutment portion operable in the planes of the sear and said first means, respectively, and means supporting said first means for bodily adjustment from a first position in which said rst means is movable by said slide to engage said second means to release said sear from said hammer, and a second position in which said first means is free of said second means for all positions of said slide.

"7. In an automatic weapon having a receiver,

`a slide reciprocably mounted on said receiver,` a

hammer oscillatively mounted in said receiver, a trigger pivotally mounted on said receiver and a sear tiltably mounted on said receiver adjacent the trigger and releasably engageable with said hammer, the combination therewith of selector means manually operable into at least two positions, a rst means mounted on said selector means and adapted to be actuated by the slide means, a second means having a body portion movably mounted adjacent the sear and adapted to trip the same, a sear tripping portion extending normal from said body portion, an abutment member extending from said body portion oppositely from said sear tripping portion, an offset plunger housing on said body portion, and a spring pressed plunger in said housing adapted to abut said receiver, whereby in one position of said selector means said first means is moved into operative engagement with said slide, to cause said sear tripping portion to tilt said sear to release the hammer and in the other of said positions of said selector means to render said iirst means inoperative to cause tilting of the sear tripping portion to eiect such release of the hammer.

8. In a weapon having -a receiver, a slide reciprocably mounted on said receiver and a sear tiltably mounted on said receiver, the combination therewith of an adjustable support on the receiver, a rst means mounted on said support, a second means mounted on the receiver, said iirst means having,r portions operable in and engageable with the said second means and the slide, respectively, said second means adapted to engage the sear to tilt the same, and means for adjusting said support to shift bodily said first means either into or out of operative engagement with the slide whereby said rst means will or will not, respectively, cause tilting of said sear.

9. In a gun having a receiver, a bolt reciprocable on said receiver, a slide reciprocable on said receiver to drive said bolt in one direction, a sear movably mounted on the receiver, the combination therewith of means on said receiver adapted to engage the sear for moving the same, an actuating means engaging said rst named means and the slide whereby movement of the slide Will effect movement of the sear, and means on the receiver for displacing bodily said actuating means relative to the slide whereby movement of the slide is ineffective to effect movement of the sear.

10. In an automatic rearm having a bolt, a gas operated reciprocable member engageable with said bolt to retract the same, and a spring.. pressed hammer arranged to strike a firing member, a sear, means movably mounting said sear for engagement with said hammer to releasably secure said hammer in cocked position, a sear release member, means movably mounting said sear release member on said rearm in cooperative to strike a ring member slidably mounted by said bolt, a sear engageable with said hammer to secure said hammer in a cocked position, a sear release member movably mounted on the firearm and cooperating with said sear to move said sear out of engagement with said hammer, an elongated link movably mounted on the rearm longitudinally thereof, said link forming an operating connection between said sear release member and said reciprocable member, and

means for selectively relating said link with saidV reciprocable member between a first position wherein said link is moved by said reciprocable member to contact and thereby operate said sear release member only as said reciprocating member approaches its battery position and a second position wherein said link is out of contact with said reciprocable member for all positions of the latter.

12. In a weapon having a receiver, a slide reciprocably mounted on said receiver and a sear tiltably mounted on said receiver, the combination therewith, of a rst lever means, sliding contact means on said iirst lever means and engageable by said slide to pivot said rst lever means, a second lever means having portions thereof operable in the planes of said sear and said first lever means for engagement therewith, respectively, fulcrum means on the receiver pivotally supporting said first lever means, and manually operable means on the receiver for adjusting said fulcrum means between a rst position wherein said slide engages said contact means to actuate said rst lever means to cause tilting of the sear, and a second position in which said first lever means is clear of said slide for all positions of the latter.

FREDERICK W. SAMPSON.

PAUL H. HAMISCH.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 544,657 Browning Aug. 20, 1895 836,713 Schouboe Nov. 27, 1906 933,254 Knous Sept. 7, 1909 1,308,016 Clark June 24, 1919 1,333,498 Lang Mar. 9, 1920 1,444,890 Swebiluis Feb. 13, 1923 2,308,283 Humeston Jan. 12, 1943 2,356,727 Reising Aug. 22, 1944 2,371,012 Woodhull Mar. 6, 1945 2,388,487 Johnson Aug. 28, 1945 2,388,443 Ruger Nov. 6, 1945 FOREIGN PATENTS Number Country Date 231,050 Great Britain Mar. 26, 1925 

